Where does “五月蝿い” come from?

五月蝿い (Japanese) comes from Japanese い, from Japanese や, from Japanese じゃ, from Japanese である, from Japanese で, from Japanese ぜ, from Japanese ぞえ, from Japanese え.

Ancestry of “五月蝿い”, step by step

五月蝿い traces back through 3 separate lines of ancestry.

via Japanese い

Step	Language	Word	Meaning
1	Japanese	い	Used in compounds with certain sentence-ending...
2	Japanese	や	and/or; is, are; Alternative form of いや
3	Japanese	じゃ	so, then—used for connecting to a reasonable...
4	Japanese	である	To be: the copula, with the same function as だ and its polite form です
5	Japanese	で	at; with, by, using; indicating the following...
6	Japanese	ぜ	sentence-ending particle signifying emphasis,...
7	Japanese	ぞえ	sentence-ending particle signifying emphasis, used to lightly press one's point, with affectionate overtones
8	Japanese	え	Alternative form of い
9	Middle Chinese	衣	—

via Japanese 五月

Step	Language	Word	Meaning
1	Japanese	五月	the month of May; the fifth month of the lunar...
2	Middle Chinese	月	—

via Japanese 蝿

Step	Language	Word	Meaning
1	Japanese	蝿	a fly

Every word from Middle Chinese 衣 →Every word from Japanese え →Every word from Japanese ぞえ →